1. Technical Field
This invention relates to techniques and structures for the dissipation of thermal energy generated by electronic devices. More particularly, the present invention relates to conduction elements for cooling electronic devices in single device or multi-device integrated circuit packages assemblies where the devices are mounted on substrates with solder bonds, and the heat sink or cover mounted in close proximity to the devices.
The high circuit densities in modern integrated circuit devices require that the heat generated by their operation be efficiently removed in order to maintain the temperature of the devices within the limits that will keep the operating parameters of the devices within predetermined ranges, and also prevent the destruction of the device by overheating. The problems of heat removal are increased when the device is connected to the supporting substrate with solder terminals. In such solder bonded devices, the heat transfer that can be accomplished through the solder bond is limited, as compared to back bonded devices.
Cooling of electronic devices can be achieved by immersing the devices in a suitable liquid coolant. However, these cooling methods can result in corrosion of the device and substrate metals, and also present rework problems. Cooling can also be achieved by providing a conducting link of material between the device and the cap or cold plate.
This invention is an improved structure for conduction cooling of electronic devices solder bonded to a substrate where the heat is removed from the back side of the device to a cap or cold plate.
2. Background of the Invention
The following documents relate to various structures for removing heat from a solder bonded electronic device.
U.S. Pat. No. 4,415,025 issued Nov. 15, 1983 to Horvath for "Thermal Conduction Element for Semiconductor Devices" discloses a package containing a disk shaped thermal bridge comprising a bulge shaped disk with a first set of inwardly extending slots and a second set of outwardly extending slots emanating from the center of the disk.
U.S. Pat. No. 4,442,450 issued Apr. 10, 1984 to Lipschutz et al. for "Cooling Element for Solder Bonded Semiconductor Devices" discloses a package containing a thermal bridge which includes a thick metal sheet provided with cuts that define at least one tab element containing grooves to make it bendable and a spring means to selectively urge the tab element into contact with the device.
U.S. Pat. No. 4,156,458 issued May 29, 1979 to Chu et al. for "Flexible Thermal Connector For Enhancing Conduction Cooling" discloses a heat conductive metallic foil bundle with micro-slices to provide flexibility.
U.S. Pat. No. 4,770,242 issued Sept. 13, 1988 to Daikoku et al. for "Cooling Devices of Semiconductor Chips" discloses a thermal bridge device comprising interlaced fin members whose contact force between the device and its housing is accomplished through use of a spring.